Metallized device

ABSTRACT

A diamond body and an oxide substrate are simultaneously sputter-etched such that the diamond body is cleaned and a layer of the sputtered oxide is deposited on the clean surface of the diamond body, then a metallic layer is deposited on the oxide layer. This provides a metallized diamond body whose metallic layer will adhere to the body.

This is a division, of application Ser. No. 490,792, filed July 22,1974, now U.S. Pat. No. 3,945,902.

BACKGROUND OF THE INVENTION

This invention relates to a metallized body of crystalline material andto a method of fabricating. More specifically, the present inventionrelates to a diamond material that has been metallized and to the methodfor metallization of a diamond material.

In the past, it was difficult to metallize a crystalline diamondmaterial so that the metallization would adhere to the material. In theprior art, sputtering techniques have been used for the metallization ofcrystalline material such as diamonds, but such techniques had severaldistinct disadvantages. Sputtering a metal onto a diamond surface, inthe prior art, required the diamond being placed in an evacuatedsputtering system in which the diamond was first sputter etched and thenmetallized. Both steps had to be performed consecutively in theevacuated sputtering system. The vacuum system could not be brokenbetween process steps since to assure adhesion of the metal onto thediamond it is essential that the diamond surface be cleaned as a resultof the sputter etching. In addition, since prior art metallization of adiamond material must be performed in a sealed sputtering system, theentire surface of the diamond is covered with a metallic layer, becauseit is not convenient to introduce a selective mask into the vacuumsystem to form a metallic pattern.

SUMMARY OF THE INVENTION

A metallized diamond device including a body of diamond material havinga layer of an oxide material on the surface of the body. Such ametallized diamond device can be fabricated by a method of metallizing abody of crystalline material in which simultaneously a crystalline bodyis cleaned and an oxide layer is formed on the cleaned body. Themetallic layer can be patterned by masking using photoresist technology.If however, the metallic layer is etched so as to form a pattern, aportion of the diamond surface may be exposed to the ambient and anyfurther metallization onto the exposed surface is not possible withoutagain sputter-etching the diamond surface. Sputter-etching the diamond asecond time would remove all metallization initially formed on thediamond surface. Therefore, it would be most advantageous to have amethod of metallizing a diamond in which metallization can be performedon the diamond after the diamond has been removed from thesputter-etching chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the metallized body of diamondmaterial of the present invention.

FIG. 2 is a cross-sectional view of an apparatus suitable for theoperation of the method of the present invention.

FIG. 3 is a cross-sectional view of the metallized body of diamondmaterial of the present invention, having a patterned metallic layer.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a metallized device 10 consists of a body ofdiamond material 12 having an oxide layer 14 on a surface of the body12. On the oxide layer 14 is a metallic layer 16. The oxide layer 14 istypically an oxide of silicon or aluminum, but silicon dioxide is ispreferred since it is used extensively in photoresist technology. Themetallic layer 16 is typically gold with a layer of any good wettingagent, such as titanium or chromium, between the gold and the oxidelayer 14, to assure adherence of the gold.

Referring to FIG. 2, an apparatus suitable for carrying out the methodof fabricating a metallized crystalline body such as the metallizeddevice 10 is generally designated as 110. The apparatus 110 comprises asputtering chamber 111 in which is a cathode plate 115 and an anodeplate 118. The anode plate 118 is separated from and directly over thecathode plate 115. The plates 115 and 118 are typically of a metal suchas brass. An oxide substrate 114 is placed on the cathode plate 115.Bodies of crystalline material 112, typically diamonds, are disposedonto the oxide substrate 114, between plates 115 and 118. The bodies ofcrystalline material 112 are the same as the body of crystallinematerial 12 in FIG. 1, and the oxide substrate 114 is of the samematerial as the oxide layer 14 in FIG. 1.

After the crystalline bodies 112 have been disposed on the substrate114, the sputtering chamber 111 is closed and sealed, so as to beimpervious to the ambient. Next, the sputtering chamber 111 isevacuated, by a vacuum pump 120, to approximately 5 × 10⁻⁶ mm Hg. Afterevacuation of the sputtering chamber 111, the chamber 111 is back filledfrom a source 122 of a heavy noble gas. Usually, of the noble gases thatcan be used in sputtering the inert gas, argon is preferred since it isboth inexpensive and efficient as compared to other noble gases.

With the sputtering chamber 111 back filled with argon gas at a pressuresuitable for sputtering, such as from 25 to 50 microns pressure, thecathode plate 115 and the anode plate 118 are electrically connected toan RF power source (not shown) such that the cathode plate 115 is at anegative potential compared to the anode plate 118. The RF voltagedifferential between the plates 115 and 118 must be sufficient for theoperation of the sputtering process. That is to say, the RF voltagebetween the plates 116 and 118 must be at such a value as to ionize theargon atoms between the separated plates effecting a glow dischargetherebetween, and then accelerate the argon ions toward the targets tobe sputter-etched. The voltage potential difference between the plates115 and 118 forms positive argon ions. Therefore, the argon ions will beattracted to and accelerated toward the cathode plate 115, striking theoxide substrate 114 and crystalline bodies 112.

The argon ions are large as compared to the atoms of the materialsconstituting the oxide substrate 114 and crystalline bodies 112. Whenthe argon ions strike the oxide substrate 114 and crystalline bodies 112they cause some of the atoms in the area of the striking ion to beejected from the surfaces of the oxide substrate 114 and crystallinebodies 112. Some of the ejected crystalline atoms and oxide atoms willbe attracted to the anode plate 118 and be deposited thereon. Since thesputtering rate of the oxide substrate 114 is greater than thesputtering rate of the bodies of crystalline material 112, at some timein the sputtering process a layer of oxide will form on the crystallinebodies 112. In the method of the present invention the oxide substrate114 and crystalline bodies 112 are sputter-etched simultaneously and anoxide layer is deposited onto the surface of the crystalline bodies 112.

The atoms forming an oxide layer on the surface of the crystallinebodies 112 come from two sources. The first source is atoms which havebeen ejected from the surface of the oxide substrate 114 and whichstrike argon ions in the glow discharge and are reflected back towardthe surfaces of the crystalline bodies 112. The second source is fromthose atoms which have been ejected from the oxide substrate 114 andhave been deposited onto the anode plate 118. Some of these ejectedatoms will in turn be ejected from the anode plate 118 and deposited onthe crystalline bodies 112.

Typically, after about 2 hours of sputter etching at an RF-AC voltagedifferential of between 1400 and 1600 volts a layer of oxide materialabout 400 to 500 A in thickness has been deposited on the crystallinebodies 112. The crystalline bodies 112 are then removed from thesputtering chamber 111 and either metallized or placed in a storage forfuture metallization.

Since the body of diamond material 12, as shown in FIG. 1, is coatedwith an oxide layer 14, methods well known in the art, such asevaporation, can be used to form the metallic layer 16 on the oxidelayer 14. Having the oxide layer 14 on the body of diamond material 12improves the adherence of the metallic layer 16 of the metallized device10, since an oxide, such as silicon dioxide, has a better adherentquality to both diamond and a metal, such as gold, than the gold has tothe diamond. By the use of state of the art masking and photoresisttechniques, the metallic layer 16 of FIG. 1 can be formed into manydesired patterns.

Referring to FIG. 3, the metallized device 210 consists of a body ofdiamond material 212 having an oxide layer 214 on a surface thereof, anda patterned metallic layer 217 on the oxide layer 214. The body ofdiamond material 212 and the oxide layer 214 are the same as the body 12and oxide layer 14, respectively, of the metallized device 10 of FIG. 1.Those portions of the oxide layer 214 which are exposed, because themetallic layer 217 is patterned, are designated as 219. If after thepatterned metallic layer 217 is formed, the metallized device 210 is toagain be metallized, it can be done with the method of the presentinvention since metallization on the exposed portion 219 of the oxidelayer 214 and on the metallic layer 217 can be performed in the ambient.Unlike in the prior art methods of metallization, there is no need inthe method of the present invention to again subject the device 210 tosputter etching before metallizing. The method of the present inventionis far more flexible than that provided by prior art methods ofmetallization in a sealed sputtering system.

Therefore, the metallized device 10 and the method of the presentinvention, provides for a metallic layer on a diamond body which willnot peel off from the body and a method of performing multi-metallicsteps on crystalline bodies. A metallized crystalline material such as adiamond can be useful as a heat sink for many types of semiconductordevices where thermal dissipation is important. In addition, since apatterned metallic layer can be formed onto the metallized diamond, thepresent invention has an application for the stylus of phonographicdevices.

We claim:
 1. A metallized diamond device comprising:a body of diamondmaterial of silicon or aluminum having a thickness of 400 to 500A havinga layer consisting essentially of an oxide material on a surfacethereof, and a metallic layer on said oxide layer.
 2. A metallizeddiamond device comprising:a body of diamond material having a layerconsisting essentially of an oxide material of silicon or aluminumhaving a thickness of 400 to 500A on the surface thereof, and apatterned metallic layer on said oxide layer.